Automatic locking acceleration actuated vehicle safety belt retractor

ABSTRACT

An automatic locking vehicle safety belt retractor includes a shaft on which is affixed a belt take up reel having similar first ratchet wheels at its opposite ends. A spring retracted transverse pawl member includes pawl teeth which are rockable with the pawl member into and out of braking engagement with the ratchet wheels and the pawl member is drive coupled to an internally toothed second ratchet wheel rockably mounted on the shaft. A fly wheel is freely rotatable on the shaft within the second ratchet reel and carries a spring retracted second pawl swingable into engagement with the second ratchet wheel and a cam wheel is rotatable with the shaft and engages a cam follower on the second pawl to advance the second pawl upon rotation of the cam wheel relative to the fly wheel. The numbers of teeth on the second ratchet wheel and on each of the first ratchet wheels are equal and the cam and ratchet wheels are so angularly related that when the retractor is braked, the pawls fully engage respective ratchet teeth.

BACKGROUND OF THE INVENTION

The present invention relates generally to improvements in vehiclesafety belt retraction devices, and it relates particularly to animproved automatic locking safety belt retractor reel which responds toa belt withdrawal exceeding a predetermined rate.

In order to restrain a vehicle seat occupant against forward motion inthe event of a sharp or rapid slowing of the vehicle's forward motion,such as that accompanying a collision or similar occurrence whileaffording free and unhampered movement to the seat occupant, undernormal vehicle conditions it is a common practice to take up the safetybelt by a spring biased retractor reel which permits free withdrawal ofthe safety belt except under rapid vehicle deceleration conditions,under which conditions the reel is automatically locked against beltwithdrawal. One type of such reel responds to the belt withdrawal speedexceeding a predetermined rate to lock the reel against furtherwithdrawal. While the reel may respond to any desired belt pull, itshould advantageously respond to the pull exceeding 0.3 G. This type ofreel which has been heretofore available possesses numerous drawbacksand disadvantages. They are complicated, bulky, expensive devices oflimited application, difficult and inconvenient to install, and oflittle versatility and adaptability.

SUMMARY OF THE INVENTION

It is a principal object of the present invention to provide an improvedvehicle safety belt retrator.

Another object of the present invention is to provide an improvedautomatic locking vehicle safety belt retractor reel.

Still another object of the present invention is to provide a safetybelt retraction reel which automatically locks against belt withdrawalwhen the belt is withdrawn under a pull exceeding a predetermined value.

A further object of the present invention is to provide a device of theabove nature, characterized by its high reliability, great compactness,low cost, ease and convenience of installation, and great versatilityand adaptability.

In a sense, the present invention contemplates the provision of anautomatic locking safety belt retractor comprising a shaft, a take-upreel mounted on and rotatable with the shaft, and spring biased in abelt rewind direction, a safety belt, connected to and retractable byand withdrawable from the reel, a first ratchet wheel rotatable with thereel, a first pawl mounted for movement between positions engaging anddisengaging the first ratchet wheel, a second ratchet wheel mounted onand rotatable relative to the shaft, a fly wheel rotatably mounted onthe shaft, a second pawl mounted on the fly wheel and movable therewithand movable relative to the fly wheel between positions, engaging anddisengaging the second ratchet wheel, and a cam member mounted on androtatable with the shaft and engagable with the second pawl, wherebyrotation of the cam member a predetermined angle in advance of the flywheel by the rotation of the shaft at a predetermined acceleration inresponse to a predetermined pull on the belt effects the actuation ofthe second pawl by the cam member into engagement with the secondratchet wheel to forwardly rock the second ratchet wheel, and actuatingmeans drive coupling the second ratchet wheel and the first pawl wherebyforward rocking of the second ratchet wheel advances th first pawl intoengagement with the first ratchet wheel to lock the reel against beltwithdrawal rotation, the first and second ratchet wheels having equalnumbers of ratchet teeth. In addition, the cam member and the first andsecond ratchet wheels are angularly related about the shaft, so that thefirst and second pawls simultaneously engage the bases of ratchet teethon the first and second ratchet wheels respectively.

In the preferred form of the retractor, the shaft is journalled betweenthe side walls of a U-shaped bracket which rockably supports a cross barhaving a pair of first pawls which are proximate a pair of first ratchetwheels at opposite ends of the reel. The second ratchet wheel isinternally toothed and surrounds the fly wheel and the second pawl whichis pivotally mounted on the fly wheel. The means coupling the first pawlcarrying cross bar and the second ratchet wheel, includes a transverseleg extending from the bar and engaged by an arm which includes a pinslideably engaging a radial slot in an end wall of the second ratchetwheel.

The improved retractor reel is rugged, simple, reliable, inexpensive andcompact, and is simple and convenient to install even in restricted andlimited spaces. The control components which require close tolerancesmay be injection molded of polymeric resin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of an automatic locking beltretractor embodying the present invention;

FIG. 2 is a fragmentary front elevational view thereof;

FIG. 3 is a side elevational view;

FIG. 4 is a sectional view taken along line X--X in FIG. 2, showing theretractor in its normal operating condition;

FIG. 5 is a view similar to FIG. 4, showing the retractor in its lockedcondition;

FIG. 6 is a side elevational view of another embodiment of the presentinvention;

FIG. 6' is a perspective view of a component thereof; and

FIG. 7 is a side elevational view of a further embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, particularly FIGS. 1 to 5 thereof whichillustrate a preferred embodiment of the present invention, thereference numeral 1 generally designates a U-shaped bracket or framewhich constitutes the main support body of the retractor by which it issecurely mounted to the floor or seat, or other suitable portion of theautomotive vehicle. A shaft 3 having secured thereto reel 4 is rotatablymounted between the upright side walls of the frame 1, the reel 4 beingattached, in turn, to one end of a safety belt 2. A cap-shaped returnspring cover 5 and a helical return spring 6 are located on the outsideface of a side wall of the U-shaped frame 1, the ends of return spring 6being fastened to the cover 5 and the shaft 3 and operative to keep thesafety belt 2 wound up on the reel 4 by its resilient recoiling force.Ratchet wheels 7,7' are fitted or otherwise secured to both ends of thereel 4 proximate the frame side walls.

A pawl member 8 is mounted in proximity to the ratchets 7,7' andincludes a cross bar rockably engaging opposing segment shaped openings9,9' formed in the side walls of the frame 1 and pawl teeth 10,10'projecting from the cross bar of the pawl member 8 and engageable withratchet teeth 7,7'. A return spring 11 engages one end of the cross barof the pawl member 8 and resiliently biases the pawl member 8 out ofmeshing engagement with the ratchet teeth 7,7' by the pawl teeth 10,10'.A cap-shaped ratchet latch wheel 12 made of a polymeric resin materialand having the same number of internal ratchet teeth as those of each ofthe ratchet wheels 7,7' is mounted on the portion of shaft 3 projectingbeyond the opposite side wall of the frame 1 and is rockable andrestricted against axial movement by an E-shaped ring 13. The outersurface of the end wall of the latch wheel 12 has several bosses 14, bywhich the latch wheel 12 is rotatable with reduced friction on theconfronting face of the side wall of the frame 1.

An elongated opening or slot 15 is formed in the end wall of the ratchetwheel 12 for coupling to a bent part or transverse tongue 17 on the pawlmember 8 by engagement with an end pin 18 located on a pawl memberactuating arm 16, to which the bent part 17 of the pawl member 8 issecured as by spot welding. Thus, the pawl member 8 is actuated by therotation or rocking of the latch wheel 12. An inertia.Iadd. , support.Iaddend.or fly wheel 20 made of metal is freely rotatably carried byshaft 3 inside of the latch wheel 12 and held by an E-shaped ring 13'against axial displacement on the shaft. The inertia wheel 20 has smallholes 21,21', and a stepped pin 22' is suitably anchored in the hole 21'while another stepped pin 22 registers with a fulcrum opening 24 in apawl 23 and is suitably anchored in the hole 21, the pawl 23 thus beinglightly slideable on the surface of the inertia wheel 20. The free endpart of the pawl 23 has a spring engaging aperture 25, by which atension spring 26 connected to stepped pin 22 is retained. The pawl 23is normally resiliently urged or biased by spring 26 towards a cam wheel27, later to be described, and out of meshing engagement with the latchwheel 12. The cam wheel 27, an undulate ring spring 28 and a stopperplate 29 are fitted to the shaft 3 and retained thereon by the E-shapedring 13". The cam wheel 27 is made of a polymeric resin material andpress fitted on the shaft 3. Segment shaped peripherally extendingcamming recesses 30 are formed in the surface of the cam wheel 27 facingto the inertia wheel 20.

As the inertia wheel 20 is rotated with rotation of cam wheel 27 butwith a time lag, the camming recesses 30 act on the inwardly directedcam follower part 31 of the pawl 23, thereby rotating the pawl 23outwardly and urging the pawl 23 into engagement with a ratchet tooth ofthe latch wheel 12. The cam wheel 27 is urged towards the inertia wheel20 by the ring spring 28 backed by the stop plate 29 and constrained bythe E-shaped ring 13'. The inertia wheel 20 has a light surface contactwith the cam wheel 27 to keep the inertia wheel 20 from oscillation. Thepawl 23 and the cam 30 are also uniformly maintained in their normalpositions to prevent fluctuations in the sensitivity of the inertiasystem. In order to synchronize the operation of the ratchet wheels 7,7'with that of the latch wheel 12 under conditions of locking operation,the latch wheel 12 is turned partially counter-clockwise until the pawlteeth 10,10' of the pawl member 8 are in full meshing engagement withcorresponding teeth of the ratchet wheels 7,7', that is, with the basesof the teeth, and the cam wheel 27 is then adjustably turned partiallycounter-clockwise until the pawl 23 is in complete engagement with thebottom or base of a tooth of the latch wheel 12. The cam wheel 27 ismounted fast on the shaft 3 in this position.

In operation, when the safety belt 2 is withdrawn at an ordinary ornormal speed, the reel 4, shaft 3, E-shaped ring 13", ring spring 28,stop plate 29, cam wheel 27, E-shaped ring 13' and inertia wheel 20 aresimultaneously turned with the rotation of the shaft 3. The pawl 23 ispulled by the tension spring 26 and rotated in unison with the inertiawheel 20, as it is received in the camming recess 30 of the cam wheel27. Thus, the latch wheel 12 is stationary and the pawl member 8 is helddisengaged from the ratchets 7,7' under the influence of the spring 11.The safety belt 2 can then be withdrawn or retracted as desired with thebody movement of the vehicle seat occupant. When a load higher than 0.3G is suddenly applied to the safety belt 2 by the seat occupant'sforward movement, in the case of some abnormal situation encountered bythe automotive vehicle such as sharp deceleration, and the safety belt 2is suddenly withdrawn, the cam wheel 27 starts its rapid rotation withthe shaft 3. The inertia wheel 20 starts its rotation with the cam wheel27, but with a certain time lag, because the inertia wheel 20 is fittedloosely on the shaft 3 and is made of metallic material and thus hasconsiderable weight. Thus, the cam follower part 31 of the pawl 23 ispushed upwards by the face of the camming recess 30 of the cam wheel 27,as shown in FIG. 5. The pawl 23 is swung outwardly about opening 24 as afulcrum and against the force of the spring 26, the free end part of thepawl 23 thus engaging the ratchet teeth of the latch wheel 12. The pawl23 is rotated by the rotation of the cam wheel 27 thereby causing theturning of the latch wheel 12 to thereby swing the pawl teeth 10,10' ofthe pawl member 8 into engagement with the ratchet wheels 7,7' and thusbring the rotation of the reel 4 to a stop. In this locking process,when the pawl 23 is completely engaged with the ratchet teeth of thelatch wheel 12 and the wheel 12 starts its rotation, the latch wheel 12is synchronized with the ratchet wheels 7,7', so that the end parts ofthe pawl teeth 10,10' are kept in the position of the tooth tips of theratchet wheels 7,7'. The latch wheel is thus rotated until the pawlteeth 10,10' are engaged completely with the tooth bottom regions of theratchet wheels 7,7'. At this time, the ratchet wheels 7,7' are rotatedsimultaneously into complete meshing with the pawl teeth of the pawlmember 8. With the ratchet wheels 7,7' thus engaged with the pawl teeth10,10' the reel 4 is locked against belt withdrawal rotation to keep thesafety belt 2 from further extraction, thereby restraining the occupantin his seat and promoting his safety.

The embodiments of the present invention illustrated in FIGS. 6 to 7 ofthe drawings differ from that first described only in the manner ofdrive coupling the latch wheel 12 to the pawl member 8. Thus, in theembodiment shown in FIGS. 6 and 6', an acutating lever 16' is enlargedbetween its end and provided with an opening rotatably engaging theshaft 3 proximate the end wall of latch wheel 12. One end of the lever16' terminates in a thickened yoke portion 19' which engages the tongue17 projecting from the end of the cross bar of pawl member 8 and a pin18' projects from the other end of lever 16' into sliding engagementwith the slot 15 in the latch wheel end wall. In the embodimentillustrated in FIG. 7, a radial projection is integrally formed on theoutside peripheral face of latch wheel 12 and has an enlarged radialrecess 12' formed therein which slideably engages the tongue 17 on pawlmember 8, so that rocking of the latch wheel 12 swings the pawl member8. In operation, and in all other constructional details andrelationships, the embodiments last described are similar to that firstdescribed.

The conventional emergency locking and winding mechanisms of the presenttype are usually provided with a complicated clutch mechanism to protectthe sensor unit from excessive load application and prevent theincomplete locking at the time of operation. This results in thedeficiencies and errors in sensitivity and in increased difficulty inproducing a compact device. With the mechanism of the present invention,the device may be made highly compact due to omission of the complicatedclutch mechanism as used in the conventional device. Moreover thevarious defects as encountered in the conventional apparatus at the timeof emergency may be obviated without any reduction in the reliability ofoperation.

While there have been described and illustrated preferred embodiments ofthe present invention, it is apparent that numerous alterations,additions and omissions may be made without departing from the spiritthereof.

I claim:
 1. An automatic locking safety belt retractor comprising ashaft, a take-up reel mounted on and rotatable with said shaft andspring biased to in a belt rewind direction, a safety belt connected toand retractable by and withdrawable from said reel, a first ratchetwheel rotatable with said reel, a first pawl mounted for movementbetween positions engaging and disengaging said first ratchet wheel, asecond ratchet wheel mounted on and rotatable relative to said shaft, afly wheel rotatably mounted on said shaft, a second pawl mounted on saidfly wheel and movable therewith and movable relative to said fly wheelbetween positions engaging and disengaging said second ratchet wheel, acam member mounted on and rotatable with said shaft and engagable withsaid second pawl whereby rotation of said cam member a predeterminedangle in advance of said fly wheel by the rotation of said shaft inresponse to a predetermined pull on said belt effects the actuation ofsaid second pawl by said cam member into engagement with said secondratchet wheel to forwardly rock said second ratchet wheel, and actuatingmeans drive coupling said second ratchet wheel and said first pawlwhereby forward rocking of said second ratchet wheel advances said firstpawl into engagement with said first ratchet wheel to lock said reelagainst belt withdrawal rotation, said first and second ratchet wheelshaving equal numbers of ratchet teeth.
 2. The retractor of claim 1wherein said first and second ratchet wheels and said cam member are soangularly related that said first and second pawls when actuated totheir engaged positions engage the base portions of correspondingratchet teeth of the respective first and second ratchet wheels.
 3. Theretractor of claim 1, including a first spring resilient biasing saidfirst pawl toward its ratchet disengage position and a second springresiliently biasing said second pawl toward its ratchet disengageposition.
 4. The retractor of claim 3 comprising a mounting bracketincluding a pair of transversely spaced side walls, said shaft extendingbetween and projecting beyond and journalled to said side walls, a pairof said first ratchet wheels disposed at opposite ends of said reelproximate the confronting faces of said bracket side walls, a transversecross bar extending between and rockably supported by said bracket sidewalls proximate said first ratchet wheels, and a pair of said firstpawls located on said cross bar and rockable between positions engagingand disengaging respective first ratchet wheels.
 5. The retractor ofclaim 4 wherein said fly wheel, second ratchet wheel, said second pawland said cam member are located on said shaft along the outside face ofone of said bracket side walls.
 6. The retractor of claim 4, whereinsaid second ratchet wheel is internally toothed and is cap shaped andprovided with an end wall journalled on said shaft, and fly wheel andsecond pawl being disposed within the space delineated by said secondratchet wheel.
 7. The retractor of claim 4, wherein said second ratchetwheel end wall has a radially extending slot formed therein, and saidactuating means comprises a lever engaging and rockable with said crossbar and provided with a follower element remote from said cross barslideably engaging said slot.
 8. An emergency locking type vehiclesafety belt retractor, comprising a U-shaped frame 1; a shaft mountedintermediate the upright sides of the U-shaped frame, said shaft looselycarrying on one outside of the frame, a cap-shaped latch wheel withinternal teeth, an inertia wheel fitted with a pawl, a cam wheel pressfitted on the shaft, a spring washer fitted on the shaft, and a stopplate also fitted on the shaft; ratchet wheels provided to both insidesof the U-shaped frame and having the same number of teeth as those ofthe latch wheel; a belt-winding reel press fitted on the shaft; a pawlplate mounted intermediate the upright sides of the frame and in theproximity of the ratchet wheels; and a pawl plate actuating platetransversely extending from an end part of pawl plate; wherein, when thevehicle is subjected to an abrupt impact or sudden change in theoperating state, said inertia wheel operates to rotate with the camwheel, but with a time lag when the belt is suddenly extracted, the pawlon the inertia wheel thus engaging with the latch wheel to rotate thelatter, thereby engaging the pawl plate with the ratchet wheels throughthe pawl plate actuating plate and preventing further reeling out of thesafety belt; and wherein the number of teeth of the ratchet wheels isequal to that of the latch wheel to make the pivot angle of the ratchetwheels and that of the latch wheel equal to each other to synchronizethe movement of the ratchet wheels with that of the pawl plate byadequate selection of the angle of operation of the latch wheel and thefulcrum distance of the pawl plate and the pawl plate actuating plate..Iadd.
 9. An automatic locking safety belt retractor comprising arotatable take-up reel spring biased in a belt rewind direction, asafety belt connected to and retractable by and withdrawable from saidreel, a first ratchet wheel rotatable with said reel, a first pawlmounted for movement between positions engaging and disengaging saidfirst ratchet wheel, a second ratchet wheel coaxial with and rotatablerelative to said first ratchet wheel, a second pawl rotatable with saidfirst ratchet wheel and movable between positions engaging anddisengaging said second ratchet wheel and normally urged to said ratchetwheel disengage position, actuating means for urging said second pawlinto engagement with said second ratchet wheel, and means drive couplingsaid second ratchet wheel and said first pawl whereby rocking of saidsecond ratchet wheel advances said first pawl into engagement with saidfirst ratchet wheel to lock said reel against belt withdrawal rotation,said retractor being characterized by said first and second ratchetwheels having equal numbers of ratchet teeth..Iaddend..Iadd.
 10. Theretractor of claim 9 wherein said actuating means includes meansresponsive to a predetermined rotational parameter of said reel formotivating said actuating means..Iaddend. .Iadd.
 11. The retractor ofclaim 9 wherein said first and second ratchet wheels, said first andsecond pawls, said actuating means and said drive coupling means are sorelated that said first pawl when advanced to its ratchet wheel engageposition engages the base portion of a tooth of the first ratchetwheel..Iaddend. .Iadd.
 12. An automatic locking safety belt retractorcomprising a shaft, a take-up reel mounted on and rotatable with saidshaft and spring biased to rotate in a belt rewind direction, a safetybelt connected to and retractable by and withdrawable from said reel, afirst ratchet wheel rotatable with said reel, a first pawl mounted formovement between positions engaging and disengaging said first ratchetwheel, a second ratchet wheel mounted on and rotatable relative to saidshaft, a support wheel mounted on said shaft, a second pawl mounted onsaid support wheel and means responsive and movable relative to saidsupport wheel in response to a predetermined rotational parameter ofsaid reel for moving said second pawl between positions engaging anddisengaging said second ratchet wheel whereby a predetermined pull onsaid belt effects the actuation of said second pawl into engagement withsaid second ratchet wheel to forwardly rock said second ratchet wheel,and means drive coupling said second ratchet wheel and said first pawlwhereby forward rocking of said second ratchet wheel advances said firstpawl into engagement with said first ratchet wheel to lock said reelagainst belt withdrawal rotation, said first and second ratchet wheelshaving equal numbers of ratchet teeth..Iaddend. .Iadd.
 13. The retractorof claim 12 wherein said first and second ratchet wheels, said firstpawl, said second pawl moving means and said drive coupling means are sorelated that said first pawl when actuated to its engaged positionengages the base portion of a tooth of the first ratchet wheel..Iaddend..Iadd.
 14. The retractor of claim 12 including a first springresiliently biasing said first pawl toward its ratchet disengageposition and a second spring resiliently biasing said second pawl towardits ratchet disengaging position..Iaddend..Iadd.
 15. The retractor ofclaim 14 comprising a mounting bracket including a pair of transverselyspaced side walls, said shaft extending between and projecting beyondand journalled to said side walls, a pair of said first ratchet wheelsdisposed at opposite ends of said reel proximate the confronting facesof said bracket side walls, a transverse cross bar extending between androckably supported by said bracket side walls proximate said firstratchet wheels, and a pair of said first pawls located on said cross barand rockable between positions engaging and disengaging respective firstratchet wheels..Iaddend..Iadd.
 16. The retractor of claim 15 whereinsaid support wheel, second ratchet wheel, and said second pawl arelocated on said shaft along the outside face of one of said bracket sidewalls..Iaddend..Iadd.
 17. The retractor of claim 15, wherein said secondratchet wheel is internally toothed and is cap shaped and provided withan end wall journalled on said shaft, and said support wheel and secondpawl being disposed within the space delineated by said second ratchetwheel..Iaddend..Iadd.
 18. The retractor of claim 15, wherein said secondratchet wheel end wall has a radially extending slot formed therein, andsaid actuating means comprises a lever engaging and rockable with saidcross bar and provided with a follower element remote from said crossbar slideably engaging said slot..Iaddend.